1. Field of the Invention
The present invention is directed to the field of nano-technology. In particular, the present invention is directed to nano-batteries or micro-batteries, as well as to their manufacture and use.
2. Prior Art
Nano-technology has been variously described as a shotgun marriage of chemistry and engineering and as a fabrication technology in which objects are designed and built with the individual specification and placement of each separate atom. The first unequivocal nano-fabrication experiments are said to have taken place in 1990, with the deposition of individual xenon atoms on a nickel substrate to spell the logo of a certain very large computer company. The term xe2x80x9cnano-technologyxe2x80x9d itself was allegedly coined by K. Eric Drexler, in his book xe2x80x9cEngines of Creationxe2x80x9d, where it was predicted that nano-technology could give rise to replicating assemblers, permitting an exponential growth of productivity and wealth.
Manufactured products are made from atoms, and their properties depend on how those atoms are arranged. Molecular manufacturing, in particular, involves the use of nano-scale mechanical systems to guide the placement of reactive molecules, thereby building complex structures with atom-by-atom control.
This degree of control is a natural goal for technology: Micro technology strives to build smaller devices; materials science strives to make more useful solids; chemistry strives to synthesize more complex molecules; manufacturing strives to make better products. Each of these fields requires precise, molecular control of complex structures to reach its natural limit, a goal that has been termed molecular nano-technology. It has become clear that this degree of control can be achieved.
As computer, medical and other devices become smaller, there is a need to produce smaller storage batteries to power these devices.
Previous work in the open literature referring to nano or micro-batteries has dealt almost exclusively with thin film work. (See, for example: Park, Y. J., Park, K. S., Kim, J. G., Kim, M. K., Kim, H. G., Chung, H. T., J. Power Sources (2000) 88 (2), 250; Park, Y. J., Kim, J. G., Kim, M. K., Kim, H. G., Chung, H. T., Park, Y., J. Power, Sources (2000) 87 (1-2), 69; Levasseur, A., Vinatier, P., Gonbeau, D., Bull. Mater. Sci. (1999) 22 (3), 607; Han, K. S., Tsurimoto, S., Yoshimura, M., Solid State Ionics (1999) 121 (1-4), 229; Park, Y., Kim, J. G., Kim, M. K., Chung, H. T., Um, W. S., Kim, M. H., Kim, H. G., J. Power Sources (1998) 76 (1), 41; Brojerdi, G., Tyuliev, G., Fargues, D., Eddrief, M., Balkanski, M., Surface and Interface Analysis, (1997) 25 (2) 111-118; Lee, S. J., Lee, J. K., Kim, D. W., Baik, H. K., Lee, S. M., Journal of the Electrochemical Society (1996) 143 (11) L268-L270; and Jones, S. D., Akridge, J. R., Solid State Ionics (1996) 86-8 Part 2 1291-1294.) In these papers, the so-called micro-batteries are systems where very thin films of electrolyte material were used to construct the battery, or the potential for these films to be used in batteries was discussed. The actual size of the batteries based on the size of the electrodes was much greater than the nanometer scale. Kinoshita, Song, Kim and Inaba (See: Kinoshita, K., Song, X., Kim, J., Inaba, M., Kim, J., Journal of Power Sources (1999) 82 170-175.) have discussed the conceptual design for a carbon-based rechargeable lithium micro-battery and the progress in fabricating the electrode micro structure. This technology is based on photoresists technology commonly used in the semiconductor industry. The work described here uses a different technology to develop a more complete nano or micro-battery system.
It is the inventors"" good faith belief that there have been no disclosures/publications of any significant work of this kind performed either in the general area of xe2x80x9cnano-batteryxe2x80x9d technology, nor specifically in the development of a device or process similar to the ones disclosed herein.
It would appear, therefore, that a process or method for manufacturing, using nano-technological techniques and principles, a micro-device which is able to solve the problem of providing power to nano-machines, does not currently exist.
It is, therefore, a principal object and purpose to provide a nano storage battery.
It is an additional object and purpose of the present invention to provide a manufacturing process to produce a nano storage battery.
The present invention provides a manufacturing process that can be implemented and a device created whereby nano-battery or micro-battery systems can be built, charged and even tested as set forth and described herein.
The present invention involves the fabrication of nano-battery systems that have electrode dimensions of less than 200 nanometers or micro-battery systems that have electrode systems greater than 200 nanometers up to 100 micrometers.
These battery systems may be made by using porous membrane technology. Membranes already exist that have pores from one (1) micron (1000 nm) to less than 100 nm in diameter. Existing known membranes are today used for filtration purposes.
These membranes have pores that have been successfully filled with polymer electrolyte materials either by extrusion of the molten polymer through the membrane or by using capillary forces to xe2x80x9cpullxe2x80x9d the liquid, molten polymer through the pores. (See, for example: N. Korzhova, S. L. Fisher, M. Lee Granvalet-Mancini, and D. Teeters, xe2x80x9cIonic Conduction in Polymer Electrolyte/Microporous Membrane Composites,xe2x80x9d Proceedings of the American Chemical Society Division of Polymeric Materials: Science and Engineering, 217th meeting of the ACS, Mar. 21-25, 1999, Anaheim, Calif. (American Chemical Society, Washington, D.C. 1999), p. 618.)
The next step in the fabrication is the placement of electrodes on the electrolyte-filled pores. Experiments in the Applicants"" laboratory and work done by other researchers (See, for example: Nagatomo, T., Kakehata, H., Ichikawa, C., and Omoto, O., J. Electrochem. Soc., (1985) 132 1380; and Nagatomo, T., Kakehata, H., Ichikawa, C., and Omoto, O., Synth. Met., (1987) 18, 649, Kinoshita, K., Song, X., Kim, J., Inaba, M., Kim, J., Journal of Power Sources (1999) 82 170-175.) have shown that an electrically conducting polymerxe2x80x94such as polyacetylenexe2x80x94can be used as an electrode for battery application. The Applicants have developed a liquid suspension of polyacetylene particles having a particle size that will just cover the membrane pores without passing through the pores, thus capable of making the electrodes for the nano-battery systems.
The positioning of the polyacetylene particles over the openings may be monitored by using atomic force microscopy (xe2x80x9cAFMxe2x80x9d) or scanning electron microscopy (xe2x80x9cSEMxe2x80x9d).
The present invention also involves charging of nano-batteries or micro-batteries and monitoring their voltage. The charging of the system may be accomplished using a current-sensing AFM, where an electrically-conducting cantilever tip will be touched to the electrode; a current will be applied; and the system will be charged. The AFM tip touching the electrode will then be used to monitor the voltage output of the system and other electrochemical characteristics, and tests can be conducted such as cyclic voltametery, a.c. impedance spectroscopy and battery charge/discharge cycling.
The present invention involves numerous embodiments. In one embodiment, a solid polymeric electrolyte is incorporated into a nano-molecular or micro-molecular membrane pore. The pore is preferentially lined with a non-conductive polymer. The pore is then capped with an electrode. In such cases the membrane can be selectively removed with the lining from the filled pore (or visa-versa), and a solid particulate nano-battery or micro-battery is formed. Such an isolated nano or micro-battery may be then in placed appropriately on the desired site such as, e.g., a micro-machine.
In a second embodiment, a porous membrane has its pre-sized pores at least partially filled with a solid or liquid electrolyte. This electrolyte-filled or partially filled pore is then capped with an electrode. The emplaced micro-battery or nano-battery may be charged and serve as an energy source or depot on the membrane surface. Micro-machines moving about the membrane surface, may contact the depot and receive its stored energy. Likewise, the micro-machine or other energy recipient could be emplaced and the membrane containing the charged micro or nano-batteries moved such that the emplaced energy recipient could contact the energy stored in the pore-filling micro or nano-battery.
In another embodiment, a pore having a diameter measured in nanometers or micrometers, may be emplaced on a micro-machine or other such small device requiring energy. The emplaced pore could be at least partially filled with an electrolyte and capped with an electrode. This nano-battery or micro-battery, emplaced upon the prospective energy recipient may be charged as described elsewhere herein and used by the machine or device appropriately as an energy source.
Yet other embodiments of the invention, upon an understanding of the accompanying descriptions may be envisioned by those of skill in the art.